Reactivity

• Halogens


  Elements in group 7 of the periodic table
• Reactivity of halogens


  • Decreases down group 7
  • Florine is the most reactive
  • Chlorine is less reactive than Florine
• Halogens reacting with metals

  Halogen atom gains one electron to achieve a full outer energy level
• Attraction of outer electrons to nucleus

  Greater in Florine than Chlorine due to:

  • Shorter distance between outer energy level and nucleus in Florine
  • Less shielding of outer electrons by inner electrons in Florine
• More reactive halogen can displace less reactive halogen from aqueous solution of its salt
• Displacement reaction


  More reactive halogen displaces less reactive halogen
• Displacement reactions


  • Florine displacing bromine from sodium bromide solution
  • Chlorine displacing iodine from potassium iodide solution
  • Bromine not displacing chlorine from lithium chloride